Mark Ruffalo loves to tell the story that when he had his breakthrough role in the Off-Broadway play This Is Our Youth, in 1996, a Los Angeles casting director approached him, flush with the discovery of a hot new talent, and said something like, “Where have you been hiding?” And he replied, “I’ve been doing theater just blocks away from you for years!”

That’s the paradox of L.A. theater in a nutshell: nobody seems to know how good it can be and has been, and what great talents are slogging away at it, because of the persistent perception that L.A. is not a theater town. That perception is just plain wrong, though there’s a handy explanation for it. If, by some counts, more stage productions open in L.A. annually than anywhere else in the world, that’s one of the root problems: too many of those 1,000-plus productions are, admittedly, staged merely as showcases for actors or writers eager for the film industry’s attention (though, as Ruffalo’s story indicates, good luck with that). That actor’s-showcase tendency may not be as prevalent as some people seem to think, but it’s common enough that it’s practically a rite of passage of living in L.A. to be invited by an actor friend to see him or her do third-rate Sam Shepard in some rat-trap theater with sketchy parking. It’s hard to blame Jimmy Im, who recently wrote about the For the Record movie-scene cabaret series, for assuming that L.A. theater is otherwise “dead.”

Au contraire, Mr. Im and fellow skeptics. As the editor of Back Stage West for a decade and an L.A. theater fan of long standing (I’m now an editor at American Theatre magazine in New York), I can testify to the intermittent but inarguable greatness of the stage work there. Herewith, some highlights of my L.A. theatergoing:

1. The downtown scene. I was lucky enough to work at the Downtown News in the late 1980s and early 90s, when the Mark Taper Forum, L.A.’s answer to Lincoln Center, was producing back-to-back Pulitzer winners The Kentucky Cycle and Angels in America (before they went to Broadway to be savaged and embraced, respectively), and the Los Angeles Theatre Center, L.A.’s answer to the Public Theater, was hosting Chicano comedy trio Culture Clash and lavish avant-garde extravaganzas by mad genius Reza Abdoh. Slightly farther afield, scrappy theater was being staged in a side room of the legendary punk watering hole, Al’s Bar. L.A.T.C. quickly lost its city backing but puttered along, later hosting the local premiere of Stephen Sondheim’s Assassins and Laural Meade’s exquisite piece of meta-theatrical vaudeville, Harry Thaw Hates Everybody.

2. The El Centro corridor. In the mid to late 90s, one unprepossessing street in Hollywood, not far from the Paramount lot, was the epicenter of theatrical creativity. At the charmingly vintage Cast Theatre, slacker auteur Justin Tanner staged a series of fast, funny, brilliant hit comedies, including the long-running Zombie Attack! and Pot Mom (which anticipated much of the premise of Weeds by roughly a decade), as well as a few with the aforementioned Mr. Ruffalo. And up the street the Actors’ Gang, a troupe founded by Tim Robbins and some fellow U.C.L.A. theater grads, was on a tear with a series of retooled classics (Peer Gynt with Jack Black, a modern-dress Oresteia), the musical Bat Boy, and—best of all—ensemble-devised work helmed by writer/director Tracy Young on themes of feminism (Hysteria), drugs (Euphoria), and the unconscious (Dreamplay). The Gang has since decamped to Culver City, Young now directs mostly at the Oregon Shakespeare Festival, and Tanner still writes plays, though he may be better known now for the Highland Park-based Web series, Ave 43.

3. The city as subject. If L.A. theater is commonly misperceived as a vacuous wasteland, it’s partly a function of larger misperceptions about L.A. as the Botox-gorged playground of airhead stars, cutthroat agents, and beach bums who’ve never cracked a book. That was almost never the L.A. I knew, not only because I lived in historic Echo Park but because I followed theater groups like Cornerstone Theater Company, who make plays about, with, and in the far-flung multicultural communities of Watts, Boyle Heights, Pacoima, et al. One of the high points of my theatergoing life, truly, was the culmination of Cornerstone’s playmaking residency in Watts in the mid-90s: playwright Lynn Manning set his adaptation of Brecht’s Caucasian Chalk Circle as The Central Ave. Chalk Circle in a dystopic near-future California, and director Bill Rauch’s inspired cast was a mix of Cornerstone pros and community members of all ages. Cornerstone hasn’t quite cornered the market on only-in-L.A. product: when it’s not importing the latest hit from New York, the Mark Taper Forum has occasionally deigned to stage plays about the city, such as Culture Clash’s Chavez Ravine, about the razing of that historic neighborhood to build Dodger Stadium. Meanwhile, from its theater in Little Tokyo, East West Players keeps up a steady program of plays and musicals by and about Asian Americans; even when the shows aren’t set in L.A. (Sondheim’s Pacific Overtures, David Henry Hwang’s M. Butterfly), the work is unmistakably local.

4. Evidence Room and the ensemble boom. The 2000s were dominated by companies of youngish upstarts, infused by expats from such theater towns as Seattle and Chicago, who staged ambitious, large-cast plays most big-budget theaters wouldn’t touch. From the aforementioned Actors’ Gang to Zoo District to Circle X to Open Fist to Theater of NOTE to Black Dahlia to the Furious Theatre to the 24th Street, this was a time of real aesthetic ferment and daring on the boards, in which you’d be more likely to see great new plays by U.S. and world playwrights on L.A.’s small stages than on its bigger ones. The hub of this movement was the Evidence Room, which opened a cavernous warehouse space near downtown L.A. with Chuck Mee’s crazy-quilt The Berlin Circle (another Brecht Chalk Circle adaptation, oddly enough), starring then-rising star Megan Mullally and a recent Chicago transplant named Nick Offerman (that’s how this famous couple met, in fact). That company has since become itinerant under director Bart DeLorenzo and stages a play a year (last year’s Annapurna, which starred Offerman and Mullally, is up in New York right now), and while some of those storied ensembles of a decade ago have dissolved, that path-breaking new-play energy has continued in such diverse venues as Pasadena’s Theater @ Boston Court, Mid-Wilshire’s Rogue Machine Theater (which also recently took a play to New York, John Pollono’s Small Engine Repair), and Hollywood’s Sacred Fools.

5. The standbys. L.A. theater doesn’t run solely on young actors with a passion and nothing to lose; as an industry hub, L.A. attracts every kind of performer, including the classically trained and New York-seasoned variety, and they, too, like to keep up their stage chops while they’re waiting for their pilots to get picked up. That means you can see top-flight musical theater actors doing the latest Michael John LaChiusa tuner (at the Blank Theatre) and great classical performers doing, well, the classics (The Antaeus Company, A Noise Within). And it should be said that all those upstart companies that caught my fancy in the 2000s were building on the work of such still-going troupes as L.A.’s Fountain Theater, Hollywood’s Matrix Theatre Company, Venice’s Pacific Resident Theater, West L.A.’s Odyssey Theatre, Topanga’s Theatricum Botanicum, and Burbank’s Colony Theater, among others.

And that's all without mentioning another L.A. landmark, the Groundlings, that tiny improv powerhouse on Melrose where I first saw Will Ferrell, Chris Kattan, Will Forte, Jennifer Coolidge, and Cheri Oteri strut their stuff. That’s because it hardly needs mentioning: the Groundlings may be the one theater in town that casting directors and agents have actually heard of and don’t shy away from. If only they knew all the other good stuff they’re missing.